To provide a method of feeding a powder release agent by which the capability of a powder release agent can sufficiently be exhibited, and a die-cast product stable in quality can be cast at the time of performing casting using the powdery release agent in a die casting machine performing injection/filling in a state where the inside of a cavity is made into a high vacuum state.

After the completion of mold clamping, the valve body 24 of a vacuum valve is opened, and a vacuum tank A130 for sucking a powder release agent is operated. When a powder release agent PS is discharged from a nozzle 122 to the feed port 96a of an injection sleeve 96 in accordance with a command for the powder release agent to be fed, it is sucked/exhausted from a runner part Rn, a cavity C, an exhaust path Ep and an exhaust path 25 to a vacuum system tank A through conduits 150 and 132, so that, by using the flow of air at the inside of the cavity C generated by the exhaust, the powder release agent is sufficiently diffused, and is stuck to the inside face of the cavity.